Electrode



vMay 1s, 1926.`

D. M.. slMoNs ELECTRODE Filed. Nov. 19,

1924 A 2 Smeets-Sme*v ILII 'IH'HL Hain.

May 18,1926. 1,585,126

D. M. SIMONS ELECTRODE Filed Nov. 19l 1924 2 Sheets-Sine??I 2 IFIC-3.1112.

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Patented May 18, 1926.

UNITED. STATES PAIrENT OFFICE.

DONALD M. SIMONS, OF OSBORNE, PENNSYLVANIA, ASSIGNOR TO STANDARD UNDER- GROUND CABLE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTRODE.

Application led November 19, 1924. Serial No. 750,740.

. My invention relates to the construction of electrodes; it concerns a modification in the shape of an electrode, such as to prevent electrostatic discharge; and it concerns an 'extension of the surface of the electrode, in immediate association with a body of solid insulation. The structure is such that no spaces can occur, between the surfaces of the conductor and of the body of insulation. Thus sparking and glowing are guarded against. In certain applications for Letters Patent of the United States which already I have filed, I have described specific prac? tical embodiments of the invention which in this application I shall claim in broader aspect. These prior applications area.n application filed September 18, 1924, Serial No. 7 38,424, cable joint, and an application tiled October 15, 1924, Serial No. 743,645, terminal.

My present invention, embodied as I have said, in my earlier applications, is, for present purposes illustrated in the accompanying drawings, in which Fig. I is a View in medial andl longitudinal section, showing diagrammatically the invention embodied in a cable-end, as that cable-end might appear, when subject t0 test in a laboratory. Fig. II is a diagrammatic.view in plan of a sheet of material employed in the building of the structure of Fig. I. Fig.' II is positioned relative to Fig. I in such manner as to indi- Figs. III and IV are views similar to Figs. I and II, respectively, and show the inventionembodied in a cable joint.

In Fig. I, I showaI cable from which, adjacent its end, the sheath has first been cut away, exposing the envelope 1 of machine'- laid insulation, and from which for a less distance the machine-laid insulation too has been vcut away, leaving the end 2 of the con-l ductor exposed. Sucha cable-end s ov prepared is ready for certain tests to be `performed upon it. It may or may not, for the purpose of these. tests, be submerged in oil, as Fig. I of the drawings indicates it to be. The problem which my invention,v solves is, how tov prevent breakdown, from the bared conductor-end, through whatever dielectric' may lie between, to an adjacent body. of metal. In Fig. III I similarly show two cable-ends, from which the sheaths have been cut away, exposing the envelopes 1 of ma.- ch1ne-laid insulation, and from which the envelopes of insulation have in turn beenl for less distances cutaway, exposing the conductors 2. The conductors are electrically united, as by the sweated-on sleeve of metal 3, and the problem is to prevent electrostatic discharge from the corner of this sleeve over the surface of envelope 1, to the cptziaway end of the cable sheath, indicated a In any electrical installation, bodies on which lines of force terminate when differences of potential exist are properly termed electrodes.

Comparing Figs. I and III, it will be perceived that in both cases there is an electrode (the bared -conductor-end 2, Fig. I; the edge ofthe sleeve 3, Fig. III), electrostatic discharge from which to an adjacent body of conducting material, is to be prevented. Reference to vmy earlier applications mentioned above will/reveal the fact that in themtoo the same problem is met. In them, however, the electrode to which a protective structure is added, is not the active, current-carrying conductor, nor any part of it, but is the cut-away end of the cablesheath. It will, however, be manifestfrom the disclosure of this specification alone, that the invention I am about to describe is applicable to electrodes generally.

Referring first to Fig. I, my invention is achieved by wrapping upon the bared end 2 of the conductor and advantageously, though not necessarily, upon the adjacent stepped end of the envelope of machine-laid insulation, a long web of suitable insulating material, such as paper, which preferably' in a single wrap shall form the insulating body 5. This web of paper is provided with a strip of metal, and the strip of metal is so laid and disposed upon the web of paper that, when the-paper has been applied, the` metal will form the body 6, incorporated with the body 5 of wrapped-on paper. The metal strip which the web of paper carries extends to that ed e 0f the web, where wrapping begins, or su stantially so, and in consequence the body 6 is electrically continuous with the conductor.

Fig. II shows the web of paper in plan before it is wrapped upon the parts to be protected. In this ligure the web of paper is indicated at 9, and the strip of metal which the web of paper carries is indicated at 8. It will be perceived that as the web of paper shown in Fig. II is wrapped upon the otherwise bare cable end of Fig. I, forming around lthe cable end the envelope 5, the strip of metal 8 will form within the body of insulation the spherical metallic shell 6. This spherical shell will be in electric continuity with the bared conductor end 2 and will constitute electrically an extended, round-surfaced enlargement of the conductor 2. This rounded surface will be incorporated in a body of solid insulation, with no spaces between surfaces of conductor and of insulation where sparking and glowing might occur. Y

Considering novir the resultant structure, it will Ibe perceived that, electrically regarded, the surface of the co-nductor has been extended in the surface of the body 6, and that, simultaneousl with the extension, the 'body 6 has been incorporated with a body of solid insulation, in such manner that the meeting of surfaces, as between the body of conductor and the body of insulation, is exact and complete: there is no intersurface space, where sparking and glowing might occur.

By the particular placement of the strip of metal upon the web of paper, the shape of the enlargement 6 of the conductor is variable anddeterminable. Fig. I shows the shape to be that of a hollow sphere, surrounding the conductor 2 at its very end. And, manifestly, the spherical surface so produced,em'bedded as 1t is'in solid insulation, affords a wide and even distribution of strain; this in a structure contained within an intimately enveloping body o f'insulation, highly resistant to the strains exerted.

In makin application of the web of paper to the bared conductor 2, a plug of insulation 7, of coiled paper or the like, may be provided as a structural extension of the body of conductor 2, upon which jointly with the bared conductor-end the body 5 may be wrapped.

The whole structure as I have described it, may then be immersed if desiredand ordinarily such will be the desirein liquid insulation, and the cable may be subjected to test. In ,such testing, the breakdown strength will -be found to have been greatly increased: the 4danger of breakdown will "be practically eliminated. y

Fig. I-II illustrates the embodiment of the invention in a cable-joint, where the electrode -to be shielded from discharge is the I before it is wrapped upon the parts to be protected. In this figure the web of paper is indicated at 9a and the strip of metal which ythe web of paper carries is indicated at 8a. It will be perceived that as the l web of paper shown in Fig. IV is wrapped upon the otherwise bare joint of Fig. III, forming around the joint the envelope 5, the strip of metal 8 will form within the body of insulation the ellipsoidal metallic shell 6a. This ellipsoidal shell will, as with the shell 6 of Fig. I, be in electric continuity With'the lbared conductor-ends 2, and the/body 6El will constitute electrically an extended, round-surfaced enlargement of the elect-rode, such rounded surface being incorporated in a body of solid insulation, with no spaces between surfaces of conductor and of insulation, where sparking and glowing might occur.

The joint of Fig. III will, it will be understood, be completed in suitable manner, as by wrapping on additional paper insulation or its equivalent, bringing to position an allenclosing joint-casing, making union of the joint-casing at its ends with the cable-sheath, and ',liushing the joint and filling the otherwise unoccupied spaces withinthe casing with insulating compound. In Fig. III a joint-casing olf familiar form is indicated in dotted lines at 10, in its ultimate position. The practice of the invention in applying to the joined conductors the body 5, does not forbid its further use in providing extensions to the cut-away ends 4 of the cablesheath, as set fortl in my earlier applications mentioned above.

Figs. II and IV show the bared ends of the envelope of machine-laid insulation to 'be stepped, and the web 9u to be cut to corresponding sha e, so that the finished body 5 shall fit neat y upon the cable-end. That structure is of course electrically considered, very secure and satisfactory. But the showing in that particular is exemplary merely; my invention lies elsewhere; and the shaping of the ends of tle bodies 'i of machinelaid insulation and cf the ends of body 5a, whether the two bodies be shaped to make substantial strface to surface contact or not, will be carried out 1n such particular man3 ner as the engineer may prefer or find adequate. Fig. IV- shows the strip 8fL of metal so la-.id upon the paper web, that when the web 1s wrapped on to form the body 5a, the

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wholeof the body 6a is contained within and beneath the surface of the body a. It will be manifest thatthe stripfSa may if desired,

extend to the edge last to bev applied to the such as oil or varnish. The body built up of such material is, in its electrical character,

v a solid body, as distinguished from a body of liquid insulation, which in its very nature is not suited to withstand the strains with which I here am concerned.

The metal strip 8 (8a) borne by the web of paper or equivalent material maybe variously applied; it may be painted on the sheet, or sprayed on, or it may be applied in the form of-foil. The sheet may itself be Vcut to receive the metal in the form of an inlay. The .strip of metal may 'be carried on one side of the web only or on both sides or may vform a section of the'web, continuous from surface to surface. If it be formed by` application to opposite surfaces, the two applications may be made electrically continuous by penetrating holes in the web of paper.

Y Ordinarily in the wrapping on of the web the successive turns of the strip will make contact turn upon turn, but this vis not necessary: an attenuated spiral will have the same effect as a built-up ellipsoid, continuous on every meridian. It isA requisite only that the body of metal be sufficient to endure under service conditions.

Preferably, as I have said the body 5- (5a) is built as a single wrap, in which the spirally laid laminations extend from end to end of the so-built structure.

The proportions given in the drawings are necessarily far from those which actually will obtain, and in this respect the drawings are diagrammatic. The numberof turns in buildingv the body 5 (5a) is in practice vastly greater than the ldrawings suggest. 'Ihe web may (particularly in the case of Fig. I) be a hundred feet long, and the convergence ofthe opposite portions of strip 8, so clearly indicated in Fig. II, will then in the practical embodiment be beyond detection by casual inspect-ion. In such matters the drawingsJ of necessity are not to be taken as literal presentments ofthe structure.

The particular shape of the body 6 .(63) developed within the wrapped-on insulation may be varied greatly, merely by varying and carrying the position of the strip.V Fig. I shows a globular body, Fig. III shows an elongate, ellipsoidal bo'dy, and manifestly the body will in its minute shape be suited to the conditi-ons of service contemplated.

It will be understood, without particular illustration, that the invention is applicable, without any change whatever, to each-of the conductors of a multiple-conductor cable, as well as to the single-conductor cable. shown.

The wrap is preferably a single web and in making such an installation as that shown 1n Fig. III, the work may readily be done in the field.

It will be apparent that, while the metal strip is preferably shaped as Idescribed above to produce a hollow enlargement of the me" tallic body, the invention will be present still, even though the enlargement be in effect not hollow, but solid. Such a modification as here is suggested will be accomplished if the sheet of Fig. II be metallized, not along converging lines merely, but over all the interval between these convergingv lines. And the modification remains still, an embodiment of my invention. In each case the enlargement of the metallic body extends in a surface of revolution with respect to the axis of the body to which'the enlargement is made. This term surface of revolution which appears in the ensuing claims is, however, a term which applies with mathematical precision in definition whenit is a body of circular cross section which is under consideration. In every case the surface so defined is a surface which` on every cross section and at all points is equidistant from the original surface of the body to which the enlargement is made, and the phrase surface of revolution as I use it will be understood as definite of a surface having that characteristic.

I claim as my invention:

1. In an electrical installation an electrode A enveloped in a wrapped-on body of solid insulation, such wrapped-on body carrying, embedded in its structure, a. built-up body of conducting material. said body of conducting material being in electrical continuity with the electrode and being disposed in a surface of revolution with respect to the axis of the electrode. f 2. In an electrical installation an electrode enveloped in a wrapped-on body of solid insulation within which a metallic extension of the electrode is embedded.

3. In an electrical installation an electrode enveloped in `a wrapped-on body of soli-d insulationof which each convolution extends without break throughout the -entire length of the envelope, said body containing a metallic extension ofthe electrode.

4. A wrapping for a conductor consisting lll of -asheet of insulating material carrying along a line oblique to its length a strip of metal.-

5. A wrapping for a conductor consisting of a sheet of insulating material bearing' a longitudinally and obliquely extending metal strip, such strip, when the Wrapping has been applied, constituting a voltagelimiting surface.

6. A wrapping for a conductor consisting of a sheet of insulating material bearing a plurality of adjacent, longitudinally-extending strips of metal, converging to union, such strips, when the wrapping has been applied, constituting a doubly Haring, limiting surface to voltage stress.

:[i1 tesimony whereof I have hereunto set BONALD SIMONS. 

